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SAE-AISI 4340M Steel vs. AISI 321 Stainless Steel

Both SAE-AISI 4340M steel and AISI 321 stainless steel are iron alloys. They have 74% of their average alloy composition in common. There are 32 material properties with values for both materials. Properties with values for just one material (4, in this case) are not shown.

For each property being compared, the top bar is SAE-AISI 4340M steel and the bottom bar is AISI 321 stainless steel.

Metric UnitsUS Customary Units

Mechanical Properties

Brinell Hardness 710
170 to 210
Elastic (Young's, Tensile) Modulus, GPa 190
200
Elongation at Break, % 6.0
34 to 50
Fatigue Strength, MPa 690
220 to 270
Poisson's Ratio 0.29
0.28
Shear Modulus, GPa 72
77
Shear Strength, MPa 1360
420 to 460
Tensile Strength: Ultimate (UTS), MPa 2340
590 to 690
Tensile Strength: Yield (Proof), MPa 1240
220 to 350

Thermal Properties

Latent Heat of Fusion, J/g 280
290
Maximum Temperature: Mechanical, °C 430
870
Melting Completion (Liquidus), °C 1440
1430
Melting Onset (Solidus), °C 1400
1400
Specific Heat Capacity, J/kg-K 480
480
Thermal Conductivity, W/m-K 38
16
Thermal Expansion, µm/m-K 13
17

Electrical Properties

Electrical Conductivity: Equal Volume, % IACS 7.8
2.4
Electrical Conductivity: Equal Weight (Specific), % IACS 9.1
2.7

Otherwise Unclassified Properties

Base Metal Price, % relative 3.9
16
Density, g/cm3 7.8
7.8
Embodied Carbon, kg CO2/kg material 1.9
3.2
Embodied Energy, MJ/kg 26
45
Embodied Water, L/kg 55
140

Common Calculations

PREN (Pitting Resistance) 2.2
19
Resilience: Ultimate (Unit Rupture Work), MJ/m3 120
190 to 230
Resilience: Unit (Modulus of Resilience), kJ/m3 4120
130 to 310
Stiffness to Weight: Axial, points 13
14
Stiffness to Weight: Bending, points 25
25
Strength to Weight: Axial, points 84
21 to 25
Strength to Weight: Bending, points 51
20 to 22
Thermal Diffusivity, mm2/s 10
4.1
Thermal Shock Resistance, points 70
13 to 15

Alloy Composition

Carbon (C), % 0.38 to 0.43
0 to 0.080
Chromium (Cr), % 0.7 to 1.0
17 to 19
Iron (Fe), % 93.3 to 94.8
65.3 to 74
Manganese (Mn), % 0.65 to 0.9
0 to 2.0
Molybdenum (Mo), % 0.35 to 0.45
0
Nickel (Ni), % 1.7 to 2.0
9.0 to 12
Nitrogen (N), % 0
0 to 0.1
Phosphorus (P), % 0 to 0.012
0 to 0.045
Silicon (Si), % 1.5 to 1.8
0 to 0.75
Sulfur (S), % 0 to 0.012
0 to 0.030
Titanium (Ti), % 0
0 to 0.7
Vanadium (V), % 0.050 to 0.1
0